The present invention relates to improved asphalt compositions. More particularly, it relates to asphalt compositions useful in road building or paving having improved resistance to weathering.
Asphalt has become widely used as binder for aggregate materials particularly for the preparation of pavements and roads. Asphalt is of organic composition and is subject to change and/or degradation as a result of the normal weathering process. Solar radiation, oxidation and water effects all combine to cause chemical and physical changes which render asphalt a less functional mastic for mineral aggregates employed in road or pavement construction. Weathering caused by solar radiation and oxidation is referred to as "age hardening" while the detrimental effects due to water exposure are referred to as "water stripping."
Commercial products are available to combat both types of weathering. Water-stripping inhibitors and inexpensive long lasting anti-oxidants have not, however, been combined in a suitable fashion in asphaltic paving compositions. It appears that both are needed in many cases to achieve increased road life to any significant degree based on the probability that the mechanism of road degradation shifts from one form of deterioration to the other depending upon which type additive is missing. It is, accordingly, an object of the present invention to provide an asphalt compositionhaving improved properties for use in paving and construction of roads.
It is another object of the invention to provide paving-type asphalt compositions having increased resistance to age-hardening. Still another object of the invention is to provide paving-type asphalt compositions which will not be stripped from mineral aggregates by water after the road and/or pavement is constructed. Other objects and advantages of the invention will become apparent from the following description thereof and the examples given below.